CN1592508A - Organic electroluminescent display with porous material layer - Google Patents

Abstract

An organic electroluminescence display (OELD), comprising: a substrate; an organic electroluminescence unit, which is arranged on the surface of the substrate, and has a pair of opposite electrodes and electrons and holes supplied by the pair of electrodes recombine to emit light an organic emission layer; a sealing member combined with a substrate to protect the organic electroluminescence unit from external air, the sealing member having a sealing portion along its edge; and a porous material layer disposed on the sealing member On the surface opposite to the organic electroluminescent unit so as not to be in contact with the sealing portion, the porous material layer includes a transparent material suitable for absorbing moisture and remaining transparent even after absorbing moisture.

Description

Organic electroluminescent display with porous material layer

Request Priority

Pursuant to 35 U.S.C. §119, this application incorporates by reference an earlier application filed with the Korean Intellectual Property Office on August 27, 2003, entitled "ORGANIC ELECTROLUMINESCENT DISPLAY WITHPOROUS MATERIAL LAYER" and assigned Serial No. All Rights Reserved.

Moreover, this application is related to a co-pending application concurrently with this application to be assigned U.S. Application Serial No. No. entitled "ORGANIC ELECTROLUMINESCENT DISPLAY WITH POROUS MATERIALLAYER". This related application has the same inventor as the present application, And claim priority under 35 U.S.C.§119 of an earlier application filed at the Korean Intellectual Property Office on August 28, 2003, entitled "ORGANIC ELECTROLUMINESCENT DISPLAY WITHPOROUS MATERIAL LAYER" and its assigned serial number No. 2003-59903.

Technical field

The present invention relates to an organic electroluminescent display, and more particularly, the present invention relates to an organic electroluminescent display having an improved sealing structure.

Background technique

Generally, an organic electroluminescent display (OELD) that emits light by electrically exciting a fluorescent organic compound is a self-luminous display that operates at a low voltage. Since OELDs can be made thin, have a wide viewing angle, and have a fast response rate, they have received great attention as next-generation displays to eliminate problems caused by liquid crystal displays.

Such an organic electroluminescence display is manufactured by forming an organic layer in a predetermined pattern on a transparent insulating substrate such as glass, and then forming electrode layers on the top and bottom surfaces thereof. In this organic electroluminescent display, when an anode voltage is applied to the anode, holes injected from the anode move to the emission layer, and when a cathode voltage is applied to the cathode, electrons injected from the cathode move to the emission layer, resulting in The holes and electrons recombine in the emissive layer to generate excitons. As these excitons transition from the excited state to the ground state, the light-emitting molecules in the emissive layer emit light, thereby forming an image.

The organic electroluminescence display deteriorates due to intrusion of moisture thereinto, so that a sealing structure for preventing the intrusion of moisture is required.

Generally, a hermetic structure consisting of a metal casing or a glass substrate formed as a recessed enclosure filled with desiccant powder has been used. In addition, a film type desiccant has been attached using a double-sided tape. Using desiccant powder complicates the manufacturing process, increases material and manufacturing costs, and increases the thickness of the substrate. Also, due to the areas filled with desiccant powder, especially when used with opaque substrates, no front or double sided emission can be obtained. Membrane desiccants are not a perfect sealing structure against moisture intrusion, and are prone to damage during manufacture or use due to poor durability and reliability. Therefore, membrane desiccants are not suitable for large-scale use.

U.S. Patent No. 5,882,761 relates to an organic electroluminescent display device comprising a stack of pairs of opposing electrodes having an emissive layer composed of an organic compound therebetween, a container for sealing the stack from the outside air, and a A desiccant in which the desiccant remains solid even after absorbing moisture. This patent suggests the use of alkali metal oxides, sulfates, etc. as desiccants. However, the organic electroluminescence display is thick due to the container. Also, although the desiccant remains solid, it becomes opaque after absorbing moisture, making it impossible to apply it to front-emitting and double-sided emitting displays. As described above, the manufacture of organic electroluminescence display devices is complicated, and the cost of materials and manufacture is high.

Japanese Laid-Open Patent Publication No. 5-335080 relates to a method of forming a protective layer in a thin organic electroluminescent display including an emissive layer containing at least one organic compound disposed between an anode and a cathode , at least one of the anode and the cathode is transparent, and the protective layer is made of amorphous silicon oxide (silica). Specifically, amorphous silicon oxide having a dense structure is applied to the second electrode layer as a thick layer to prevent intrusion of moisture from the outside. However, the amorphous silicon oxide protective layer cannot absorb the moisture present in the electroluminescent display, thus, an additional moisture absorbing material is required.

Contents of Invention

The present invention provides an organic electroluminescent display (OELD) capable of front-side emission or double-side emission because it remains transparent even when moisture is absorbed.

The present invention provides an OELD having a porous material layer which does not degrade the adhesiveness of the sealing portion.

The present invention also provides an OELD having a layer of porous material, wherein the layer of porous material is properly separated from the OEL unit to prevent Moiré.

According to one aspect of the present invention, there is provided an OELD, comprising: a substrate; an organic electroluminescent unit disposed on the surface of the substrate and having a pair of opposite electrodes, and electrons and holes supplied by the pair of electrodes recombine to emit light an organic emission layer; a sealant, combined with the substrate to protect the organic electroluminescence unit from external air, and having a sealing portion along its edge; and a porous material layer, disposed on the opposite side of the organic electroluminescence unit on the surface of the sealing member so as not to be in contact with the sealing portion, and the porous material layer is composed of a transparent material that can absorb moisture and remain transparent even after absorbing moisture.

According to a specific embodiment of the present invention, the area of the porous material layer may be equal to or larger than that of the organic electroluminescence unit. A barrier wall may also be formed between the sealing portion and the edge of the porous material layer. The sealing member may have a recessed portion having a predetermined depth in a surface thereof opposite to the organic electroluminescence unit, and the porous material layer may be disposed in the recessed portion so as not to contact the sealing portion.

The sealing member may be composed of a transparent substrate, and the porous material layer may be spaced apart from the organic electroluminescence unit by a predetermined distance to prevent moiré phenomenon caused by light emitted from the organic electroluminescence unit. The layer of porous material may be separated from the organic electroluminescent unit by at least 10 μm. The layer of porous material may be separated from the organic electroluminescent unit by no more than 1000 μm. The seal can be a glass substrate or a transparent plastic substrate. When a transparent plastic substrate is used, a waterproof protective layer may be formed on the inner surface of the transparent plastic substrate. In the opposing electrodes of the organic electroluminescence unit, at least one of the opposing electrodes opposed to the sealing member may contain a transparent conductive agent.

The porous material layer may be a porous oxide layer having a large number of absorption pores. The porous oxide layer may have a thickness ranging from 100 nm to 50 μm. The diameter of the absorption pores of the porous oxide layer is in the range of 0.5-100 nm.

According to another aspect of the present invention, there is provided an OELD, comprising: a substrate; an organic electroluminescent unit disposed on the surface of the substrate and having a pair of opposing electrodes, and the recombination of electrons and holes supplied by the pair of electrodes and an organic emission layer that emits light; a sealing member that is combined with the substrate to protect the organic electroluminescent unit from outside air and is composed of a transparent material; and a porous material layer that is disposed on the sealing member opposite to the organic electroluminescent unit. On the surface, separated from the organic emission layer of the organic electroluminescent unit by a predetermined distance to prevent moiré phenomenon caused by light emitted from the organic emission layer, and by absorbing moisture and even after absorbing moisture Constructed of transparent material that remains transparent.

According to a specific embodiment of the OELD described above, the surface of the sealing member opposite to the organic electroluminescent display may have a recessed portion, and the porous material layer may be formed in the recessed portion. The sealing member may be composed of a glass substrate, and the recessed portion may be formed by etching a surface of the glass substrate opposite to the organic electroluminescence unit. A barrier wall may be disposed between the seal and the substrate, and a layer of porous material may be formed on the seal within the barrier wall. The sealing member may be combined with the substrate by a sealing portion formed along an edge of the sealing member, and the sealing portion may include a spacer controlling a distance between the porous material layer and the organic electroluminescent unit.

The layer of porous material may be separated from the organic electroluminescent unit by at least 10 μm. The layer of porous material may be separated from the organic electroluminescent unit by no more than 1000 μm.

The seal can be a glass substrate or a transparent plastic substrate. When a transparent plastic substrate is used, a waterproof protective layer may be formed on the inner surface of the transparent plastic substrate. In the opposing electrodes of the organic electroluminescence unit, at least one of the opposing electrodes opposed to the sealing member may contain a transparent conductive agent.

The porous material layer may be a porous oxide layer having a large number of absorption pores. The porous oxide layer may have a thickness ranging from 100 nm to 50 μm. The diameter of the absorption pores of the porous oxide layer is in the range of 0.5-100 nm.

Description of drawings

A more complete appreciation of the invention, together with its additional advantages, will be readily apparent and better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings, wherein like reference characters indicate the same or like elements, wherein:

1 is a cross-sectional view of an organic electroluminescent display (OELD) according to one embodiment of the present invention;

Figure 2 is a perspective view of a porous material layer used in OELD according to the present invention;

3 is a cross-sectional view of an OELD according to another embodiment of the present invention; and

FIG. 4 is a cross-sectional view of an OELD according to yet another embodiment of the present invention.

Detailed ways

Referring to the drawings, description will be given of the organic electroluminescence display (OELD) according to the present invention

Example.

1, an OELD according to an embodiment of the present invention includes a substrate 11 made of an insulating material, an organic electroluminescent (OEL) unit 12 disposed on the surface of the substrate 11 and combined with the substrate 11 to protect the OEL unit 12 therein from Seal 13 influenced by external air. A layer 17 of porous material is arranged on the surface of the seal 13 opposite the OEL unit 12 .

The substrate 11 may consist of a layer of transparent insulating material, such as glass or transparent plastic. The sealing member 13 opposed to and combined with the substrate 11 may include an insulating substrate, as shown in FIG. 1 . In a back emitting display, which displays an image on a substrate 11, the seal 13 may comprise any non-transparent element, such as a substrate or a metal cover. In a front emission display in which an image is displayed on the seal 13, or in a double-sided emission display in which an image is displayed on both the substrate 11 and the seal 13, the seal 13 may be composed of transparent glass or transparent plastic. When the seal 13 is made of plastic, a waterproof protective layer (not shown) may be formed on the inner surface of the seal 13 to protect the OEL unit 12 from moisture. The protective layer can be made resistant to heat and chemical agents.

The OEL unit 12 formed on the substrate 11 includes a pair of opposing electrodes and at least one organic emission layer disposed between the pair of electrodes. The OEL unit 12 may be a passive matrix OEL or an active matrix OEL, which are classified according to driving methods.

As described above, the OEL cell 12 includes an anode serving as a hole source and a cathode serving as an electron source, and an organic emission layer, wherein the anode and the cathode are disposed opposite to each other. An anode, an organic emission layer, and a cathode are sequentially formed on the substrate 11 . This configuration of the OEL unit 12 is for exemplary purposes only, and the present invention is not limited thereto. Alternatively, the positions of the anode and cathode can be swapped.

The anode may consist of a transparent electrode, such as an indium tin oxide (ITO) electrode. In a back emitting display, which emits light towards the substrate 11, the cathode may consist of a reflective material, such as Al and/or Ca. In a front-emitting display, which emits light toward the seal 13 opposite to the substrate 11, or in a double-sided emission display, which emits light toward both the substrate 11 and the seal 13, by using a metal such as Mg and/or The cathode can be made transparent by forming a thin semi-transparent layer of Ag and depositing a transparent ITO layer thereon. In the back emission display, the electrode close to the substrate 11 is formed as a transparent electrode, and the electrode close to the sealing member 13 is formed as a reflective electrode. In the front emission display, the electrode close to the substrate 11 is formed as a reflective electrode, and the electrode close to the sealing member 13 is formed as a transparent electrode.

The anode and cathode may be formed in a predetermined pattern. In an active matrix display, the cathode can be formed as a whole layer using blanket deposition, and can also be formed in a predetermined pattern.

A low-molecular-weight organic layer or a high-molecular-weight organic layer may be formed as an organic layer interposed between an anode and a cathode. Alternatively, when a low-molecular-weight organic layer is used, it can be formed as a hole injection layer (HIL), a hole transport layer (HTL), an organic emission layer (EML), an electron injection layer (EML), and a stacked composite structure. layer (EIL) or electron transport layer (ETL). Various organic materials such as copper phthalocyanine (CuPc), (N,N'-bis(naphthalen-1-yl)-N,N'-diphenyl-benzidine (NPB) and tris-8-hydroxy Aluminum quinoline (Alq3). A low molecular weight organic layer can be formed by vacuum deposition.

When a high molecular weight organic layer is used, it may include HTL and EML. HTL is composed of PEDOT, while EML is composed of high molecular weight organic materials such as polyphenylene vinylene (PPV) and polyflorenes. The high molecular weight organic layer can be formed using screen printing or inkjet printing.

The organic emissive layer may include red (R), green (G) and blue (B) patterns corresponding to pixels for full-color displays.

In the OEL cell 12, when an anode voltage is applied to the anode and a cathode voltage is applied to the cathode, holes injected from the anode move into the emission layer, and electrons move from the cathode into the emission layer, resulting in a combination of holes and electrons. Excitons are generated by recombination in the emissive layer. When the excitons transition from the excited state to the ground state, the light-emitting molecules in the emissive layer emit light, forming an image. Full-color OELDs include R, G, and B pixels for gold displays.

In addition, an insulating protective layer (not shown) that may cover the top surface of the OEL cell 12 may be formed on the upper electrode of the OEL cell 12 facing the seal 13 to resist heat, chemical agents, and moisture intrusion. The protective layer can be composed of metal oxide or metal nitride.

The space region 10 arranged between the substrate 11 and the seal 13 can be evacuated or filled with an inert gas, such as neon or argon. Alternatively, the space zone 10 can be filled with a liquid having the same effect as an inert gas.

A sealing portion 14 in which the substrate 11 and the sealing member 13 are jointly bonded is formed along the edge of the sealing member 13 using a commonly used sealant 15 .

Although not shown in FIG. 1 , interconnection lines, circuits, and terminals electrically connecting electrodes of the OEL cell 12 are drawn out from the sealing portion 14 so that the OEL cell 12 can be driven.

According to the invention, a layer 17 of a porous material capable of absorbing moisture may be provided on the inner surface of the seal 13 opposite the OEL unit 12 . The porous material layer 17 is made of a transparent material. The porous material layer 17 can absorb moisture in the spatial region 10 between the substrate 11 and the seal 13 . After absorbing moisture, the porous material layer 17 remains transparent. To this end, the porous material layer 17 may consist of a porous oxide comprising several absorption pores 17b, as exemplified in FIG. 2 .

Referring to FIG. 2, the porous material layer 17 composed of porous oxide includes a frame 17a and a number of absorption holes 17b. The frame 17a serves as a building block forming the structure of the porous material layer 17, while the absorption holes 17b trap moisture therein. Due to this structure, the porous material layer 17 can be transparent before and after absorbing moisture, as described above.

Examples of porous oxides that can be used as the porous material layer 17 include: porous silica; hydrated amorphous alumina (alumina); binary compounds of porous silica and hydrated amorphous alumina; Binary or higher order compounds of at least one of metal oxides, alkaline earth metal oxides, metal halide compounds, metal sulfates, and metal perchlorides; and hydrated amorphous alumina, silicon oxide, and hydrated amorphous alumina And a ternary or higher multivalent compound of at least one of at least one of alkali metal oxides, alkaline earth metal oxides, metal halide compounds, metal sulfates and metal perchlorides.

When a porous oxide including a binary compound of hydrated amorphous aluminum oxide and porous silicon oxide is used, the porous material layer 17 may have a double-layer structure including an aluminum oxide layer and a silicon oxide layer.

According to the present invention, at least one of alkali metal oxides, alkaline earth metal oxides, metal halides, metal sulphates and metal perchlorides is trapped within the alumina network or the alumina-silica network.

When the porous material layer 17 is formed by using hydrated amorphous aluminum oxide and silicon oxide, the hydrated amorphous aluminum oxide and silicon oxide may be mixed in a ratio of 0.01:1-1:1, but not limited thereto.

Examples of hydrated amorphous alumina include bohemite (AlOOH) and byerite (Al(OH) ₃ ), which is alumina monohydrate.

Examples of alkali metal oxides include lithium oxide (Li ₂ O), sodium oxide (Na ₂ O), and potassium oxide (K ₂ O). Examples of alkaline earth metal oxides include barium oxide (BaO), calcium oxide (CaO), and magnesium oxide (MgO). Examples of metal sulfates include lithium sulfate (Li ₂ SO ₄ ), sodium sulfate (Na ₂ SO ₄ ), calcium sulfate (CaSO ₄ ), magnesium sulfate (MgSO ₄ ), cobalt sulfate (CoSO ₄ ), gallium sulfate (Ga ₂ (SO ₄ ) ₃ ), titanium sulfate (Ti(SO ₄ ) ₂ ) and nickel sulfate (NiSO ₄ ). Examples of metal halide compounds include calcium chloride (CaCl ₂ ), magnesium chloride, strontium chloride (SrCl ₂ ), yttrium chloride (YCl ₂ ), copper chloride (CuCl ₂ ), cesium fluoride (CsF), tantalum fluoride (TaF ₅ ), niobium fluoride (NbF ₅ ), lithium bromide (LiBr), calcium bromide (CaBr ₃ ), cerium bromide (CeBr ₄ ), selenium bromide (SeBr ₂ ), vanadium bromide (VBr ₂ ), Magnesium Bromide (MgBr ₂ ), Barium Iodide (BaI ₂ ), and Magnesium Iodide (MgI ₂ ). Examples of metal perchlorides include barium perchloride (Ba(ClO ₄ ) ₂ ) and magnesium perchloride (Mg(ClO ₄ ) ₂ ).

The porous material layer 17 can be formed using porous silicon oxide by applying one of various methods as follows.

First, a first mixture was prepared by mixing 0.3 g of surfactant and 0.6 g of solvent. Here, a polymeric surfactant was used, and a 1:2 mixture of propanol and butanol was used as a solvent. Next, a second mixture was prepared by mixing 5 g of tetraethyl orthosilicate (TEOS) with 10.65 g of solvent and 1.85 g of HCL.

After stirring the second mixture for about 1 hour, 2.1 g of the second mixture was mixed with the first mixture to obtain a third mixture. This third mixture is applied onto the substrate serving as the sealant 13 by spin coating, spray coating, roll coating, or the like. As an example, the third mixture may be spin-coated onto the second substrate 12 with the color filter 20 at 2000 rpm for about 30 seconds. The resulting structure was aged at room temperature for 24 hours or at 40-60° C. for 5 hours, and calcined in an oven at 400° C. for about 2 hours to burn off the polymer to form absorption pores. As a result, a porous silicon oxide layer having a thickness of 7000 Å was formed. The above process is repeated until a porous layer having a desired thickness is formed. The amount of material used to form the porous layer is not absolute. Instead, the ratio of materials should be fixed.

In another method, ammonia (NH ₄ OH) was added to 30 g H ₂ O to provide alkalinity. 10 g of TEOS was added to the alkaline solution and heated for 3 hours or longer, at which time it was stirred for hydrolysis and polycondensation reactions. An acid, which may be organic or inorganic, is added to the resulting solution.

Next, 13.2 g of a water-soluble acrylic resin solution (30% by weight) was added to stabilize the resulting mixture and stirred to obtain a homogeneous solution.

The solution was spin-coated onto the substrate serving as the seal 13 at 180 rpm for 120 seconds, and dried in a drying oven for about 2 minutes to remove residual non-evaporated solvent. These processes are repeated to form thicker porous layers.

The polymeric and organic substances were removed from the resulting structure, and heat-treated at 500° C. for 30 minutes to harden the silicone. The amount of material used to form the porous layer is not absolute. Instead, the ratio of materials should be fixed.

The porous silicon oxide layer formed by one of the methods described above includes absorption holes 17b in its structure, as exemplified in FIG. 2 . The size of the absorption hole 17b may be in the range of 2-30 nm. The size of the absorption pores 17b can be changed by adjusting the molecular weight of the polymer used in the first mixture. The absorption pores 17b may occupy about 80% of the volume of the porous silicon oxide layer. As described above, the porous silicon oxide layer can be formed by spin coating, spray coating, roll coating, or the like. The porous silicon oxide layer is mechanically and thermally stable. Porous silicon oxide layers can be fabricated using an easily controlled process.

When hydrated amorphous alumina is used, the porous oxide layer according to the present invention can be formed by coating and drying an alumina solution prepared by heat-treating a composition containing aluminum alkoxide and a polar solvent. The aluminum oxide solution can be applied by spin coating, screen printing, etc., but is not limited thereto. Examples of aluminum alkoxides that can be used include aluminum triisoproxide (Al(OPr) ₃ ), aluminum tributoxide (Al(OBu) ₃ ), and the like. The polar solvent may be at least one of pure water, ethanol, methanol, butanol, isopropanol and methyl ethyl ketone.

A hydrolytic catalyst such as nitric acid, hydrochloric acid, phosphoric acid, sulfuric acid, etc. may be further added to the composition. Optionally, polyvinyl alcohol, anti-foaming agent, etc. may be further added to the aluminum oxide solution if necessary. A detailed method of forming a porous oxide layer using hydrated amorphous alumina is as follows.

300 g of H ₂ O was heated to 80° C., 165.54 g of Al(OPr) ₃ was added thereto and stirred for 20 minutes. 1.2 g of 30% hydrochloric acid (HCL) was added to the reaction mixture and heated to 95° C., and refluxed for 3 hours to obtain a transparent alumina solution.

60g _H2O was added to 25g clear alumina solution and stirred for 20 minutes. 10 g of a 30% aqueous polyvinyl alcohol (PVA) solution (having an average weight molecular weight of 20,000 by weight) was added to the mixture and stirred for 20 minutes, and 5 g of anti-foaming agent was added to prepare the coating for the porous alumina layer solution.

The coating solution was spin-coated onto the substrate serving as the seal 13 at 180 rpm for 120 seconds, and dried in a drying oven for about 2 minutes to remove residual non-evaporated solvent. The resulting structure is heat treated to form a porous alumina layer. These processes are repeated to form thicker porous alumina layers. The amount of material used to form the porous alumina layer is not absolute. Instead, the ratio of materials should be fixed.

The method for producing the porous material layer according to the present invention using a mixture of porous silica and hydrated amorphous alumina is as follows.

As described above, a silica-forming composition comprising a silicon alkoxide and a polar solvent is added to the alumina solution prepared as described above. A porous oxide layer comprising a mixture of alumina and silica may be formed from a mixture of a silica forming composition and an alumina solution.

The silicon alkoxide used in the present invention has the following molecular formula (1). Examples of silicon alkoxides include tetraethylorthosilicate (TEOS) and the like.

Wherein R ₁ , R ₂ , R ₃ and R ₄ are each independently C ₁ -C ₂₀ alkyl or C ₁ -C ₂₀ or C ₆ -C ₂₀ alkyl.

As used in the preparation of the alumina solution, the polar solvent can be at least one of ethanol, methanol, butanol, isopropanol, methyl ethyl ketone and pure water. In addition, a hydrolyzable catalyst such as nitric acid, hydrochloric acid, phosphoric acid, sulfuric acid, etc. may be further added.

Specifically, 10 g of TEOS was added to 30 g of H ₂ O and 10 g of EtOH and stirred for 30 minutes or longer for the hydrolysis reaction. _CaCl2 was added to the reaction product and dissolved to obtain the composition for the porous silicon oxide layer.

The resulting composition was spin-coated onto a substrate at 180 rpm for 120 seconds to serve as a seal 13 and dried in a drying oven for about 2 minutes to remove residual non-evaporated solvent. The resulting structure is heat treated to form a synthetic porous oxide layer.

A method of forming a porous material layer of a structure in which at least one of an alkali metal oxide, an alkaline earth metal oxide, a metal halide compound, a metal sulfate, and a metal perchloride is trapped in a porous hydrated amorphous alumina network is as follows.

A composition containing aluminum alkoxide and a polar solvent is applied onto the surface of the substrate serving as the sealant 13, and heat-treated to form a porous oxide layer. As a result of the hydrolysis and dehydration polycondensation reactions, a porous alumina layer is formed.

Heat treatment can be performed at 100-550°C. If the temperature is lower than 100°C, organic substances such as solvents will remain in the layer. If the temperature is higher than 550° C., the glass substrate itself may be deformed.

The aluminoxo-forming composition may be applied using various methods such as spin coating, screen printing, etc., but is not limited thereto.

Examples of aluminum alkoxides that can be used include aluminum triisoproxide (Al(OPr) ₃ ), aluminum tributoxide (Al(OBu) ₃ ), and the like. The polar solvent can be at least one of pure water, ethanol, methanol, butanol, isopropanol and methyl ethyl ketone. The amount of the polar solvent may be in the range of 100-1000 parts by weight based on 100 parts by weight of aluminum alkoxide.

A hydrolyzing catalyst such as nitric acid, hydrochloric acid, phosphoric acid, sulfuric acid, etc. may be further added to the composition. The amount of the hydrolyzable catalyst may range from 0.1 to 0.9 moles based on 1 mole of aluminum alkoxide.

Additives such as polyvinyl alcohol, povidone, polyvinyl butyral, etc. may be further added to the composition, if necessary. Polyvinyl alcohol, povidone, polyvinyl butyral improve porosity and coating properties. The amount of the additive may range from 1 to 50 parts by weight based on 100 parts by weight of aluminum alkoxide. Polyvinyl alcohol, povidone, and polyvinyl butyral having an average weight molecular weight of 5,000-300,000 may be used.

The alumina composition may further include at least one of an alkali metal salt, an alkaline earth metal salt, a metal halide compound, a metal sulfate, and a metal perchloride. The amount of the alkali metal salt or alkaline earth metal salt may range from 0.1 to 0.5 moles based on 1 mole of aluminum alkoxide.

When an alkali metal salt and/or an alkaline earth metal salt is added to the composition, a porous oxide layer having an alkali metal oxide and/or alkaline earth metal oxide structure in which absorbed moisture is trapped in porous alumina is formed. A porous oxide layer having such a structure has a larger moisture absorption rate than a porous oxide layer containing only porous alumina.

Examples of alkali metal salts, which are precursors of alkali metal oxides, include sodium acetate, sodium nitrate, potassium acetate, and potassium nitrate. Examples of alkaline earth metal salts include calcium acetate, calcium nitrate, barium acetate, barium nitrate, and the like. Examples of metal halide compounds, metal sulfates and metal perchlorides listed above can be used.

A silicon-oxygen composition including a silicon alkoxide and a polar solvent may be added to the aluminum-oxygen composition. When the silicon-oxygen composition is added to the aluminum-oxygen composition, a porous oxide layer containing a mixture of aluminum-oxygen and silicon-oxygen is finally formed.

As in the preparation of the aluminum oxygen solution, the polar solvent can be at least one of ethanol, methanol, butanol, isopropanol, methyl ethyl ketone and pure water. The amount of the polar solvent may be in the range of 100-1000 parts by weight based on 100 parts by weight of the silicon alkoxide.

A hydrolytic catalyst such as nitric acid, hydrochloric acid, phosphoric acid, sulfuric acid, etc. may be further added to the composition. The amount of the hydrolyzable catalyst may range from 0.1 to 0.9 moles based on 1 mole of aluminum alkoxide. If the amount of the hydrolyzable catalyst is less than 0.1 mol, the production time increases. If the amount of the hydrolyzable catalyst is greater than 0.9 mol, it is difficult to control the production process.

The thickness of the porous material layer 17 manufactured by one of the above methods may be 100 nm-50 μm. If the thickness of the porous material layer 17 is less than 100 nm, the porous material layer 17 cannot sufficiently absorb moisture to protect the OEL unit 12 from moisture. If the thickness of the porous material layer 17 is greater than 50 μm, it takes too much time for production, thereby lowering the yield.

The porous material layer 17 is formed so as not to be in contact with the sealing portion 14 . If the porous material layer 17 contacts the region where the sealant 15 is used to form the sealed portion 14, the adhesiveness of the sealant 15 is lowered. By preventing deterioration of the adhesiveness of the sealing portion 15, the intrusion of moisture into the space region 10 and fatal defects of the OEL unit 12 can be prevented, and the OEL unit 12 can be effectively protected from external influences.

According to the present invention, in order to prevent the adhesiveness of the sealant 15 from being deteriorated, the porous material layer 17 does not extend to the sealing portion 14 . The porous material layer 17 may be larger than the OEL cell 12 for a larger moisture absorption area.

As shown in FIG. 1, in order to prevent the porous material layer 17 from contacting the sealing portion 14, the inner surface of the sealing member 13 opposite to the OEL unit 12 is recessed.

Although not shown, the corners of the recessed portion 16 may have right angles or be rounded. By forming the porous material layer 17 in the recessed portion 16, the porous material layer 17 and the sealing portion 14 are separated from each other.

Also, when the sealing member 13 having the recessed portion 16 is used in a front emission display that emits light toward the second substrate 12 or in a double-sided emission display, moiré phenomenon in the space region 10 can be prevented. When the distance L between the OEL unit 12 and the porous material layer 17 in the spatial region 10 is as small as several micrometers, Moiré phenomenon occurs in front-emitting or double-sided emitting displays due to light interference.

Generally, when the distance L between the OEL unit 12 and the porous material layer 17 is as small as several micrometers, it is difficult to precisely control the distance L during the manufacturing process. A small error in the distance L leads to staining, which causes Newton's rings which also contribute to staining due to constructive interference of specific wavelengths. Such darkening caused by Newton's rings can be prevented by forming the recessed portion 16 in the sealing member 17 so that the distance L between the OEL unit 12 and the porous material layer 17 is greater than 10 μm. The distance L between the OEL unit 12 and the porous material layer 17 may be greater than 10 μm. If the distance L is greater than 1000 [mu]m, the resulting display will become too thick. For this, the distance L should be smaller than 1000 μm.

The distance L between the OEL unit 12 and the porous material layer 17 can be varied by controlling the depth of the recessed portion 16 from the top surface of the sealing member 13 and the thickness of the sealant 15 used to seal the portion 14 . When a glass substrate is used as the sealing member 13, the recessed portion 16 may be formed by etching.

The above-described effects can be obtained by the OELD according to another embodiment of the present invention shown in FIG. 3 . Specifically, as shown in FIG. 3, a porous material layer 27 made of porous oxide is formed on the inner surface of the sealing member 23 and is separated from the sealing portion 24 by a predetermined distance, wherein the porous material layer 27 remains transparent after absorbing moisture. . In this embodiment, it is more effective that the porous material layer 27 is formed larger than the OEL unit 22 . The distance L between the porous material layer 27 and the OEL unit 22 may be in the range of 10-1000 μm to prevent Moiré phenomena, as described above. With the space 28 included in the sealant 25 forming the sealing part 24, the distance L between the first and second substrates 11 and 12 can be controlled. The substrate 21 and the OEL unit 22 are the same as those in the above-mentioned embodiments, so the description thereof will not be repeated here.

4 is a cross-sectional view of an OELD according to another embodiment of the present invention. In this OELD, the barrier wall 39 is formed between the porous material layer 37 and the sealing portion 34 so as not to contact each other. The distance L between the OEL unit 32 and the porous material layer 37 can be controlled to 10-1000 μm by the barrier wall 39 to prevent the Moiré phenomenon. The structures of the substrate 31, the OEL unit 32, the sealing member 33, and the sealing portion 34 are the same as those in the above-described embodiments, and thus description thereof will not be repeated here.

The OELD having the porous material layer according to the present invention provides the following effects.

Since the porous material layer formed on the inner surface of the sealing member remains transparent even after absorbing moisture, the OELD according to the present invention can be applied to both front-emitting and double-sided emitting OELDs, and the OELD can be reduced. thickness.

Second, since the porous material layer does not deteriorate the adhesion of the sealant, it stabilizes the structure of the display.

Third, due to proper separation of the layers of porous material, the Moiré phenomenon is prevented.

Fourth, since the porous material layer prevents the intrusion of moisture and external air, the lifetime of the OELD is extended.

While the invention has been particularly shown and described with reference to exemplary embodiments thereof, it should be understood by those of ordinary skill in the art that modifications may be made therein without departing from the spirit and scope of the invention as defined by the following claims. Various changes in form and detail.

Claims (26)

1. display of organic electroluminescence comprises:

Substrate;

Organic electroluminescence cell is arranged on the surface of substrate and has a pair of electrode of opposite and organic emission layer, and this organic emission layer is suitable for because this electronics that electrode of opposite is supplied with and hole compound and luminous;

Seal combines with substrate and is fit to the influence that the protection organic electroluminescence cell is not subjected to extraneous air, and has hermetic unit along its edge; And

Porous material layer, be arranged on seal with the organic electroluminescence cell facing surfaces on so that do not contact, be suitable for absorbing moisture and after absorbing moisture, still keep transparent transparent material even porous material layer comprises with hermetic unit.

2. display of organic electroluminescence as claimed in claim 1, wherein porous material layer has the area that is equal to or greater than organic electroluminescence cell.

3. display of organic electroluminescence as claimed in claim 1 further comprises the barrier between the edge that is arranged on hermetic unit and porous material layer.

4. display of organic electroluminescence as claimed in claim 1, wherein seal has recess, this recess has the predetermined degree of depth in itself and organic electroluminescence cell facing surfaces, and wherein porous material layer is arranged in the recess so that do not contact with hermetic unit.

5. display of organic electroluminescence as claimed in claim 1, wherein seal comprises transparency carrier, and wherein porous material layer and organic electroluminescence cell is separated predetermined distance, with the moore phenomenon that prevents to be caused by the light that organic electroluminescence cell is launched.

6. display of organic electroluminescence as claimed in claim 5 wherein separates at least 10 μ m with porous material layer and organic electroluminescence cell.

7. display of organic electroluminescence as claimed in claim 6 wherein separates porous material layer and organic electroluminescence cell and is not more than 1000 μ m.

8. display of organic electroluminescence as claimed in claim 5, wherein seal comprises at least a in glass substrate and the transparent plastic substrate.

9. display of organic electroluminescence as claimed in claim 8 further comprises the fish tail and waterproof layer on the inner surface that is arranged at transparent plastic substrate.

10. display of organic electroluminescence as claimed in claim 5, at least one comprises the electrically conducting transparent agent in the comparative electrode that wherein be oppositely arranged with seal, organic electroluminescence cell.

11. display of organic electroluminescence as claimed in claim 1, wherein porous material layer comprises the porous oxide layer with a plurality of suckings.

12. as the display of organic electroluminescence of claim 11, wherein porous oxide layer has the thickness from 100nm to 50 mu m ranges.

13. as the display of organic electroluminescence of claim 11, wherein the diameter range of the sucking of porous oxide layer is 0.5-100nm.

14. a display of organic electroluminescence comprises:

Substrate;

Organic electroluminescence cell is arranged on the surface of substrate and has a pair of electrode of opposite and organic emission layer, and this organic emission layer is suitable for because this electronics that electrode of opposite is supplied with and hole compound and luminous;

Seal combines and the suitable influence of protecting organic electroluminescence cell not to be subjected to extraneous air with substrate, and seal comprises transparent material; And

Porous material layer, be arranged on seal with the organic electroluminescence cell facing surfaces on, and separate predetermined distance with the organic emission layer of organic electroluminescence cell, and be suitable for preventing being suitable for the moore phenomenon that causes by from the light of organic emission layer emission absorbing moisture and after absorbing moisture, still keeping transparent transparent material even porous material layer comprises.

15. as the display of organic electroluminescence of claim 14, wherein seal comprise recess with the display of organic electroluminescence facing surfaces, and wherein porous material layer is arranged in the recess.

16. as the display of organic electroluminescence of claim 15, wherein seal comprises glass substrate, and wherein recess is etched into glass substrate with the organic electroluminescence cell facing surfaces in.

17. as the display of organic electroluminescence of claim 14, wherein further comprise the barrier that is arranged between seal and the substrate, porous material layer is arranged on the seal of barrier inside.

18. display of organic electroluminescence as claim 14, wherein the hermetic unit that forms by the edge along seal makes seal combine with substrate, and wherein hermetic unit comprises the sept that is suitable for controlling the distance between porous material layer and the organic electroluminescence cell.

19., wherein porous material layer and organic electroluminescence cell are separated at least 10 μ m as the display of organic electroluminescence of claim 14.

20., wherein porous material layer and organic electroluminescence cell are separated and are not more than 1000 μ m as the display of organic electroluminescence of claim 19.

21. as the display of organic electroluminescence of claim 14, wherein seal comprises at least a in glass substrate and the transparent plastic substrate.

22., further comprise the fish tail and waterproof layer that is arranged on the transparent plastic substrate inner surface as the display of organic electroluminescence of claim 21.

23. as the display of organic electroluminescence of claim 14, at least one in the comparative electrode that wherein be oppositely arranged with seal, organic electroluminescence cell comprises the electrically conducting transparent agent.

24. as the display of organic electroluminescence of claim 14, wherein porous material layer comprises the porous oxide layer with a plurality of suckings.

25. as the display of organic electroluminescence of claim 24, wherein porous oxide layer has the thickness from 100nm to 50 mu m ranges.

26. as the display of organic electroluminescence of claim 24, wherein the diameter range of the sucking of porous oxide layer is 0.5-100nm.

Images